The present disclosure generally relates to head mounted displays presenting content to users, and specifically to an illumination source inclusion in a head mounted display to illuminate a user's eye.
Head mounted displays (HMDs) may present various types of content to users. For example, a HMD presents virtual environments to users. When presenting content to a user via a HMD, a system may track position or gaze of a user's eye within the HMD to improve content presented to the user. For example, content presented by the HMD may be foveated, which reduces resolution of presented content that is outside an area where the user's eyes' are focused within the HMD. Similarly, resolution of content within the area where the user's eyes' are focused within the HMD is increased. In another example, content outside of the area where the user's eyes' are focused within the HMD is more highly compressed than content within the area where the user's eyes' are focused within the HMD.
To determine where a user's eyes' are focused within a HMD, a camera of other imaging device is often included in the HMD adjacent to imaging optics, or a hot mirror that is transparent to visible light, but reflective to infrared light used by the imaging device is positioned between the user's eyes and a display within the HMD. However, as fields of view of content resented by virtual reality, mixed reality, or augmented reality systems increase and distances between the user's eyes and the display within the HMD decrease, conventional approaches to identifying pupils of a user's eyes to determine the user's focal become increasingly difficult. While positioning an imaging device behind the display of the HMD would offset some difficulties with such conventional approaches, conventional backlights used with displays, such as liquid crystal displays, scatter and refract light, preventing an imaging device positioned behind the display from capturing images of the user's eye suitable for identifying the pupil of the user's eye.